shots suddenly all over the place

[katonahjohn]

New to the pcp world. Recently bought a Benjamin Marauder in 22, scoped, Shooting from the bench, 50 yard targets. First two range trips (30 pellets per day) accuracy fine. Third day and today the pellets were suddenly 4 inches from POA, then 2 inches, up and down, left and right from the bull. Using two different tins of pellets. Of course some were also in the bull. I can't see anything obvious looking down the barrel. Removed the shroud and still does it. Going to give the barrel a good cleaning to see if it makes a difference. Thoughts? THanks!!

 

[shambozzie]

Check you scope or if possible swap out scope and shoot another group.Also check for loose screws.

 

[RoosterCogburn]

Please don't be insulted. You DID refill right? Different spots in the fill cycle bear different results.
the shroud or barrel being bumped and moved. Fouling, Shooting at different pressure, different weight pellets.
Wind, Loose fitting somewhere. IF ALL of that is taken account for. The dreaded Barrel Gnomes or scope goblins.

 

[katonahjohn]

Check you scope or if possible swap out scope and shoot another group.Also check for loose screws.

Thanks!

 

[katonahjohn]

Please don't be insulted. You DID refill right? Different spots in the fill cycle bear different results.
the shroud or barrel being bumped and moved. Fouling, Shooting at different pressure, different weight pellets.
Wind, Loose fitting somewhere. IF ALL of that is taken account for. The dreaded Barrel Gnomes or scope goblins.

Hard to insult me (G). I get 30 shots per fill. Then back to the Palatial Colt Manor for a recharge. So I shot the pellet gun, then 100 rounds through my Ruger American Rimfire. Even with the Marauder's inaccuracy it was a good day. I'll remove the shroud give everything a good cleaning and a real good eyeball. Thinking tomorrow will be another good range day. Scope bolts are all lock-tited at 15 inch pounds of torque but I'll check all of the bolts cause you never know what jumps out of noware to bite you on the neck. Thanks again...

 

[citojaso]

Hard to insult me (G). I get 30 shots per fill. Then back to the Palatial Colt Manor for a recharge. So I shot the pellet gun, then 100 rounds through my Ruger American Rimfire. Even with the Marauder's inaccuracy it was a good day. I'll remove the shroud give everything a good cleaning and a real good eyeball. Thinking tomorrow will be another good range day. Scope bolts are all lock-tited at 15 inch pounds of torque but I'll check all of the bolts cause you never know what jumps out of noware to bite you on the neck. Thanks again...

If the gun had a moderator I'd make sure it hadn't worked loose. Something easy to check.

 

[Jay308]

Clean the barrel, new barrels need cleaned more often. I would re-check scope ring/base torque. Check to make sure your breech oring is intact.

 

[Motorhead]

Breech O-ring being gone will do this as well ... if it blew out you will many times find it up on the probe ?
Load a pellet, remove magazine and safely take a shot w/o it there ... DO YOU feel a blast of air hitting your face ?

 

[Bngen3]

Check barrel shroud didn’t loosen up down towards breech and now sliding back and forth

 

[JimD]

If you have anything in front of the muzzle that might be clipping the pellets that is also something to check.

 

[Dstrac]

New to the pcp world. Recently bought a Benjamin Marauder in 22, scoped, Shooting from the bench, 50 yard targets. First two range trips (30 pellets per day) accuracy fine. Third day and today the pellets were suddenly 4 inches from POA, then 2 inches, up and down, left and right from the bull. Using two different tins of pellets. Of course some were also in the bull. I can't see anything obvious looking down the barrel. Removed the shroud and still does it. Going to give the barrel a good cleaning to see if it makes a difference. Thoughts? THanks!!

Definitely clean the barrel with some ballistol and patches. The shroud should be on, and it should be tight. Making adjustments to the tightness the shroud will change poi.

 

[coastal drifter]

don't rest the gun on the barrel, only thing I can add

 

[RickH]

Some time back I was at a CMP 10 meter match with my 2078A and group size just exploded, I was grouping 3-4 inches! The day before was fine. I didn’t even finish shooting I was so annoyed. Went home, cleaned the barrel and did general maintenance and the problem was solved. It was a new gun with maybe 300 rounds through it without cleaning the barrel and I suspect something fouled the barrel about 10 shots in. I clean each one now every 100 or so shots. Easy to do and good practice.

Rick H.

 

[coastal drifter]

scope parallax

 

[Avator]

New guns will sometimes be sporadic until the break in and settler down. I usually don't even do anything about accuracy until a get a few hundred shots down the tube. I spend that time with the chronograph and checking for leaks. I don't even need a scope on the gun for that stuff.

You mentioned having the shroud off.. did you pay attention and get the baffles and spring back in correctly? No offense intended.
BTW... even though there is a barrel band, that shroud free floats in that BB. Some folks put an o-ring in there to "trap" it. I didn't have good results doing that.

 

[katonahjohn]

Thanks all. Range report. Did all of the things I mentioned above that I was going to do. First five shots in the bullseye then problems. Scratched my head. Realized I was placing the stock in different positions on the front rest. Moving the stock so it rested just slightly forward of the trigger guard all of the shots were in the bullseye. So I'll be taking the stock off and give every thing a good look to see what/where the problem is and correct it. Just stopped by Amazon and ordered a 6.8L botttle with regulator for a tethered set up. No more of this "30 pellets and put it away". Neighbor runs a paintball shop so I've already talked to him about filling my new bottle when it shows up. Thanks again

 

[JimD]

I would check to see how flexible the stock is. You can use a piece of paper to check for clearance between the stock and shroud. If there is some and it goes away based upon where the gun contacts the rest that could be your issue. I've had a gun shoot worse because the screws holding the action to the stock were loose. Seems like it could be a bit similar. Plastic stocks tend to be more flexible. Wood stocks sometimes move due to ambient humidity changes. Sealing a wood stock in the inletting can help reduce any movement.

It is common on powder burners to glass bed the action to the stock. I've never done it on a airgun but I have on powder burners. Brownells at least used to sell a little kit for it. You have to be careful not to epoxy the action into the stock but otherwise it is not difficult. But my guess is your issue is easier to solve than that. If contact between the stock and the airtube affects the POI then the contact has to be consistent. Clearance is one way to consistency. To test if contact between the stock and airtube is a factor or the cause you can put thin shims, like pieces of a business card, in the airtube channel before tightening the stock screws. If POI is different with the shim than it is without the shim you've found your issue.

Sorry I'm rambling around but a common way to bed powder burners is with a deliberate contact pad near the end of the stock for the barrel. You might want to try a shim there and if you like those results maybe bed it that way.

 

[katonahjohn]

In the stock there is a rubber pad in the area of the sling mounting post. One bolt holding the receiver to the stock. Torqued it to 30 inch pounds. Will see how things go next range visit, not up to it today. Ordered a 6.8L carbon bottle with regulator from amazon yesterday..no more "30 shots and I'm out of air" nonsense. Tether that and I can shoot till the cows come home as us old timers used to say (G)..